Johnson, U.S. Pat. No. 4,252,547; Barradas, U.S. Pat. No. 5,735,918; and Cartellone, U.S. Pat. No. 5,837,020 are incorporated herein by reference, so that background art relating to air filtering and freshening devices need not be described in detail herein.
This invention relates to the art of air filtering devices and, more particularly, to devices which both filter pollutants from contaminated air and introduce a freshening scent to the filtered air.
Air filtering and freshening devices have been provided heretofore and generally, as shown in patents to Barradas (U.S. Pat. No. 5,735,918) and Johnson (U.S. Pat. No. 4,252,547) for example, have a fan for moving air through the device, a filtering element for removing pollutants from contaminated air, and a freshening device for adding a scent to the air. These existing devices also include a housing, within which each of the other components is situated. In the air filtering and freshening devices provided heretofore, the relative position of each of the components in the housing has led to inefficient and ineffective performance of these devices.
For example, in Barradas the fan is positioned within the housing upstream of the filter element. That is, the fan pushes the air into and through the filter element. As a result, the air exiting the filter element has a relatively low velocity and therefore does not circulate effectively. Furthermore, as the filter element becomes increasingly filled with contaminants, it is increasingly difficult for air to pass through the device. This means that the velocity of the already low velocity air being discharged from the device is further reduced as the filter element becomes increasingly dirty. Furthermore, the scent discharged in Barradas is fed by both filtered and unfiltered air due to its position in the housing relative to the filter element. As a result of this dual air feed, some contaminated or unfiltered air is output by the device. As the filter element becomes increasingly dirty and it becomes increasingly more difficult for air to pass through, so more and more unfiltered air is fed to the scent discharge and recycled into the surrounding air. Another problem with positioning the fan before the filter element is that this results in dirt and dust collecting on the motor and which dramatically reduces its service life. Finally, air flows from areas of higher pressure to areas of lower pressure. By positioning the fan upstream of the filter element, Barradas uses atmospheric pressure as the lower pressure area. Barradas therefore requires the fan to generate high pressure air having a value greater than the atmospheric pressure plus the pressure loss across the filter element. Otherwise, no air will flow through the device. This is an inefficient arrangement which creates power requirements significantly higher than are necessary.
In contrast to Barradas, Johnson positions the fan downstream of the filter elements. This makes for a more efficient use of the fan by utilizing atmospheric pressure to induce flow of air to the low pressure area created by the fan on the other side of the filter element. This arrangement also permits filtered air rather than unfiltered air to pass across the motor, eliminating the dirt and dust build up which shortens motor life. However, Johnson, like Barradas, does allow some unfiltered air to pass through and be output by the device. Converse Barradas, which has a single intake passage and dual output passages, Johnson has dual intake passages that feed a single output chamber. The first of the Johnson intakes is through a filter element in the conventional manner. The second intake flows parallel to the first but does not include a filter element. The second air intake allows air to flow into a scent chamber without being filtered. The freshened scent is introduced to the unfiltered air in the chamber and then the air is discharged into a main exhaust chamber which also contains filtered air that is flowing toward the output.
Along with the circulation of unfiltered air, another problem left unresolved by the device of Johnson is the ineffective discharge of the freshening scent. As discussed above, the device in Johnson draws unfiltered air into and through the scent chamber. The freshened air is then drawn into an exhaust chamber where it may get caught in an eddy which could retain the air in the device, or it may be diffused into the surrounding air, or it may be immediately expelled in its concentrated form. As the flow of air within the device dynamically changes, the freshened air will likely move between each of these three discharge flows. As a result, the scent output of the device in Johnson is not consistent, and a scent output control will not be effective in controlling the output of the freshening scent.
In accordance with the present invention, an air filtering and freshening device of the foregoing character is provided which avoids or minimizes the problems and inefficiencies encountered with the use thereof. More particularly in this respect, an air filtering and freshening device is provided which effectively and efficiently produces filtered and freshened air without recycling any unfiltered air. Furthermore, the air filtering and freshening device of the subject invention discharges freshened air in a consistent and effective manner which is responsive to the scent discharge control baffle.
The subject invention provides a motorized fan within the housing of the air filtering and freshening device that xe2x80x9cpullsxe2x80x9d contaminated air through the filter element and into the housing by creating a lower pressure area inside the housing, adjacent the filter element. The higher pressure of the atmosphere outside the housing causes contaminated air to flow through the filter element to the lower pressure area within the housing, thereby filtering the contaminated air. This is an efficient use of the naturally occurring atmospheric pressure, which utilizes this pressure to create flow through the device rather than working to create flow against the atmospheric pressure. The fan then xe2x80x9cpushesxe2x80x9d the filtered air out of the outlet of the housing through both an exhaust passage and a scent discharge passage.
Both the exhaust and scent discharge passages are in direct fluid communication with the motorized fan, whereby the flow of filtered and freshened air from the respective passages is not affected by the condition of the intake filter element in the drastic manner that prior filtering devices have been. Furthermore, the filtered air is xe2x80x9cpushedxe2x80x9d through the freshening device by the fan providing high velocity, filtered air concentrated with scent to be output through the scent discharge passage. This scented air is then dispersed into the surrounding atmosphere in a consistent and effective manner, regulated only by the control baffle, and without being influenced by the condition of the filter element or an inefficient flow through the house. The scent output is further enhanced by the provision of a heating element adjacent the scent element which increases the concentration of scent output.
Due to the increased effectiveness of the freshening device and the desire to maintain such effectiveness, the regular replacement of the scent element is important. Accordingly, the subject invention provides easy access to the scent element which can be removed and replaced without the use of tools. The scent element is secured within a drawer which is spring biased toward an ejected position, in which the scent element is accessible and easily replaced. By pushing the drawer against the spring bias, the drawer will return to a retracted position in which the replaced scent element is again in position to dispense freshening scent into the flowing air. If the drawer is pushed against the bias of the spring a second time, the drawer will release and the spring will bias the drawer toward the ejected position, again providing access to the scent element. As previously indicated, this is accomplished without the use of or need for tools.
Accordingly, it is one of the main objects of the present invention to provide a high efficiency air filter having a freshening device therein which can be adjusted to control the scent output without restricting the exhaust of filtered air.
Another object of the present invention is the provision of an air filtering and freshening device in which the volumetric flow of scented air is not directly influenced by the condition of the filter element.
Still another object of the present invention is the provision of an air filtering and freshening device in which the freshening device has simple controls that can be easily adjusted between a no output position and a full output position.
A further object of the invention is the provision of an air filtering and freshening device having a scent element within the freshening device which is easily accessible and replaceable without the use of or need for tools.
Yet another object of the invention is to provide an air filtering and freshening device in which the effectiveness of the scent freshening element is improved.
A further object is the provision of an air filtering and freshening device which is comprised of a minimum number of parts and is structurally simple, thereby promoting economical production of the device.